/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.jmx.support;

import java.util.Arrays;
import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.Set;
import javax.management.MalformedObjectNameException;
import javax.management.NotificationFilter;
import javax.management.NotificationListener;
import javax.management.ObjectName;

import org.springframework.lang.Nullable;
import org.springframework.util.ObjectUtils;

/**
 * Helper class that aggregates a {@link javax.management.NotificationListener},
 * a {@link javax.management.NotificationFilter}, and an arbitrary handback
 * object, as well as the names of MBeans from which the listener wishes
 * to receive {@link javax.management.Notification Notifications}.
 *
 * @author Juergen Hoeller
 * @see org.springframework.jmx.export.NotificationListenerBean
 * @see org.springframework.jmx.access.NotificationListenerRegistrar
 * @since 2.5.2
 */
public class NotificationListenerHolder {

    @Nullable
    private NotificationListener notificationListener;

    @Nullable
    private NotificationFilter notificationFilter;

    @Nullable
    private Object handback;

    @Nullable
    protected Set<Object> mappedObjectNames;


    /**
     * Set the {@link javax.management.NotificationListener}.
     */
    public void setNotificationListener(@Nullable NotificationListener notificationListener) {
        this.notificationListener = notificationListener;
    }

    /**
     * Get the {@link javax.management.NotificationListener}.
     */
    @Nullable
    public NotificationListener getNotificationListener() {
        return this.notificationListener;
    }

    /**
     * Set the {@link javax.management.NotificationFilter} associated
     * with the encapsulated {@link #getNotificationFilter() NotificationFilter}.
     * <p>May be {@code null}.
     */
    public void setNotificationFilter(@Nullable NotificationFilter notificationFilter) {
        this.notificationFilter = notificationFilter;
    }

    /**
     * Return the {@link javax.management.NotificationFilter} associated
     * with the encapsulated {@link #getNotificationListener() NotificationListener}.
     * <p>May be {@code null}.
     */
    @Nullable
    public NotificationFilter getNotificationFilter() {
        return this.notificationFilter;
    }

    /**
     * Set the (arbitrary) object that will be 'handed back' as-is by an
     * {@link javax.management.NotificationBroadcaster} when notifying
     * any {@link javax.management.NotificationListener}.
     *
     * @param handback the handback object (can be {@code null})
     * @see javax.management.NotificationListener#handleNotification(javax.management.Notification, Object)
     */
    public void setHandback(@Nullable Object handback) {
        this.handback = handback;
    }

    /**
     * Return the (arbitrary) object that will be 'handed back' as-is by an
     * {@link javax.management.NotificationBroadcaster} when notifying
     * any {@link javax.management.NotificationListener}.
     *
     * @return the handback object (may be {@code null})
     * @see javax.management.NotificationListener#handleNotification(javax.management.Notification, Object)
     */
    @Nullable
    public Object getHandback() {
        return this.handback;
    }

    /**
     * Set the {@link javax.management.ObjectName}-style name of the single MBean
     * that the encapsulated {@link #getNotificationFilter() NotificationFilter}
     * will be registered with to listen for {@link javax.management.Notification Notifications}.
     * Can be specified as {@code ObjectName} instance or as {@code String}.
     *
     * @see #setMappedObjectNames
     */
    public void setMappedObjectName(@Nullable Object mappedObjectName) {
        this.mappedObjectNames = (mappedObjectName != null ?
                new LinkedHashSet<>(Collections.singleton(mappedObjectName)) : null);
    }

    /**
     * Set an array of {@link javax.management.ObjectName}-style names of the MBeans
     * that the encapsulated {@link #getNotificationFilter() NotificationFilter}
     * will be registered with to listen for {@link javax.management.Notification Notifications}.
     * Can be specified as {@code ObjectName} instances or as {@code String}s.
     *
     * @see #setMappedObjectName
     */
    public void setMappedObjectNames(Object... mappedObjectNames) {
        this.mappedObjectNames = new LinkedHashSet<>(Arrays.asList(mappedObjectNames));
    }

    /**
     * Return the list of {@link javax.management.ObjectName} String representations for
     * which the encapsulated {@link #getNotificationFilter() NotificationFilter} will
     * be registered as a listener for {@link javax.management.Notification Notifications}.
     *
     * @throws MalformedObjectNameException if an {@code ObjectName} is malformed
     */
    @Nullable
    public ObjectName[] getResolvedObjectNames() throws MalformedObjectNameException {
        if (this.mappedObjectNames == null) {
            return null;
        }
        ObjectName[] resolved = new ObjectName[this.mappedObjectNames.size()];
        int i = 0;
        for (Object objectName : this.mappedObjectNames) {
            resolved[i] = ObjectNameManager.getInstance(objectName);
            i++;
        }
        return resolved;
    }


    @Override
    public boolean equals(Object other) {
        if (this == other) {
            return true;
        }
        if (!(other instanceof NotificationListenerHolder)) {
            return false;
        }
        NotificationListenerHolder otherNlh = (NotificationListenerHolder) other;
        return (ObjectUtils.nullSafeEquals(this.notificationListener, otherNlh.notificationListener) &&
                ObjectUtils.nullSafeEquals(this.notificationFilter, otherNlh.notificationFilter) &&
                ObjectUtils.nullSafeEquals(this.handback, otherNlh.handback) &&
                ObjectUtils.nullSafeEquals(this.mappedObjectNames, otherNlh.mappedObjectNames));
    }

    @Override
    public int hashCode() {
        int hashCode = ObjectUtils.nullSafeHashCode(this.notificationListener);
        hashCode = 29 * hashCode + ObjectUtils.nullSafeHashCode(this.notificationFilter);
        hashCode = 29 * hashCode + ObjectUtils.nullSafeHashCode(this.handback);
        hashCode = 29 * hashCode + ObjectUtils.nullSafeHashCode(this.mappedObjectNames);
        return hashCode;
    }

}
